Polyamide

ABSTRACT

A polyamide characterized in that the polyamide is obtained by thermal polycondensation of (a) dicarboxylic acid components comprising 10 to 80% by mole in total carboxylic acid components of 1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of 50/50 to 97/3 and (b) an aliphatic diamine component is disclosed. The alicyclic polyamide having 1,4-cyclohexanedicarboxylic acid in a backbone thereof as a dicarboxylic acid unit, which is suitable as materials for various uses such as automotive parts, electric/electronics parts, industrial materials, engineering materials and daily household goods, and superior in heat resistance, low water absorption, light resistance, moldability and light weight, as well as superior in toughness, chemical resistance and appearance, and molded articles thereof.

TECHNICAL FIELD

[0001] The present invention relates to a new polyamide and moldedarticles thereof. In more detail, the present invention relates to a newpolyamide superior in moldability, heat resistance, light resistance andweather resistance, as well as superior in toughness, low waterabsorption, chemical resistance and appearance. The inventive polyamideis also suitable as materials for various uses such as automotive parts,electric/electronics parts, industrial materials, engineering materialsand daily household goods, and molded articles thereof.

PRIOR ART

[0002] Polyamides, represented by nylon 6 and nylon 66, have been widelyused as materials for various uses such as clothing, industrialmaterials, automotive parts, electric/electronics parts and engineeringparts, due to superior moldability, mechanical properties and chemicalresistance.

[0003] However, with the recent demand for weight reduction of parts, asubstitute for metals used in the parts is molded polyamide. As such,the mechanical properties required for molded articles of polyamide havebeen on the increase. More specifically, conventional nylon 6 and nylon66 are not satisfactory in heat resistance, dimensional stability,mechanical properties and chemical resistance and thus cannot be used atpresent, for example, in an electric/electronics application where aheat resistance for reflow soldering is required along with adevelopment of surface mounting technology (SMT), or an application forunder-hood automotive parts where the requirements have been raised yearafter year.

[0004] A polyamide with a high melting point has been proposed torespond to these demands by solving the problems of the conventionalpolyamides. More specifically, for example, an aliphatic polyamide witha high melting point composed of adipic acid and 1,4-butanediamine(which may be abbreviated as PA46 hereinafter) and a semi-aromaticpolyamide with a high melting point mainly composed of terephthalic acidand 1,6-hexanediamine (which may be abbreviated as 6T type copolyamidehereinafter) have been proposed and some of which are practically used.

[0005] However, although PA46 has good moldability and heat resistance,it has problems of remarkably large dimensional change and lowering inmechanical properties caused by water absorption. A polyamide composedof terephthalic acid and 1,6-hexanediamine (which may be abbreviated asPA6T type hereinafter) also has a such high melting point as about 370°C., but it is difficult to obtain molded articles with satisfactoryproperties by melt molding due to vigorous thermal degradation of thepolymer itself. Therefore, a 6T type copolyamide having a loweredmelting point in a range of 220 to 340° C. has been developed and usedby copolymerizing PA6T with an aliphatic polyamide such as nylon 6 andnylon 66 or an amorphous aromatic polyamide such as nylon 6I. Said 6Ttype copolyamide really has low water absorption, high heat resistanceand high chemical resistance, but has disadvantages such as inferiormoldabilty, toughness and light resistance. Said copolyamide also has ahigh specific gravity, resulting in a problem in weight reduction.

[0006] Furthermore, an alicyclic polyamide with a high melting pointcomposed of 1,4-cyclohexanedicarboxylic acid and 1,6-hexanediamine(which may be abbreviated as PA6C hereinafter) or a semi-alicyclicpolyamide composed of said alicyclic polyamide and other nylon has beenproposed. More specifically, for example, JP-B-47-11073 disclosesimprovements in heat resistance and mechanical properties by introducinga benzene ring or a cyclohexane ring into the molecular chain of thepolyamide. JP-A-58-198439 discloses a polyamide composed of1,4-cyclohexanedicarboxylic acid, having a trans/cis ratio of 20/80 to50/50, and undecanonanediamine. RESEARCH DISCLOSURE, P. 405-417 (1991)discloses a polyamide composed of 1,4-cyclohexanedicarboxylic acidhaving a trans ratio of not less than 99% and/or isophthalic acid as acarboxylic acid component, and an aliphatic diamine having carbon atomsof 6 to 9 as a diamine component. A polyamide composed of1,4-cyclohexanedicarboxylic acid having a trans ratio of not less than99% and adipic acid, as a carboxylic acid component, andhexamethylenediamine, as a diamine component, has been also disclosed.Further, JP-A-11-512476 discloses that a semi-alicyclic polyamidecomposed of 1 to 40% of 1,4-cyclohexanedicarboxylic acid, as acarboxylic acid unit, shows an improved heat resistance for soldering.JP-A-9-12868 further discloses that a polyamide composed of adicarboxylic acid unit, in which 1,4-cyclohexanedicarboxylic acid ranges85 to 100% by mole thereof, and an aliphatic diamine as a diamine unitis superior in light resistance, toughness, moldability and heatresistance.

[0007] According to the study by the present inventors, an alicyclicpolyamide with a high melting point composed of1,4-cyclohexanedicarboxylic acid and 1,6-hexanediamine or asemi-alicyclic polyamide, which is a copolymer of said alicyclicpolyamide and other nylon, really has, to a certain extent, moreimproved moldability, heat resistance and light resistance compared withthose of the conventional nylon 6, nylon 66, the aliphatic polyamidehaving a high melting point or the semi-aromatic polyamide, but stillneeds improvement and is insufficient in such characteristics astoughness, dimensional stability in water absorption, chemicalresistance and appearance, thus its application is limited at themoment.

DISCLOSURE OF THE INVENTION

[0008] An object of the present invention is to provide an alicyclicpolyamide having 1,4-cyclohexanedicarboxylic acid as a carboxylic acidunit in a backbone thereof, and superior in moldability, heatresistance, light resistance and weather resistance, as well as superiorin toughness, low water absorption, chemical resistance and appearancesuitable as materials for various uses such as automotive parts,electric/electronics parts, industrial materials, engineering materialsand daily household goods, and molded articles thereof.

[0009] The present inventors, after an extensive study to solve theabove-described problems, found that the problems described above wereable to be solved by a new alicyclic polyamide obtained bypolycondensation of dicarboxylic acid components containing1,4-cyclohexanedicarboxylic acid having a specified trans/cis molarratio and a diamine component. In particular, the present inventorsfound that a semi-alicyclic polyamide, which was a copolymerizedpolyamide of said alicyclic polyamide with other types of nylon, wasable to effect remarkable improvements, and thus accomplished thepresent invention.

[0010] Thus, the present invention relates to a polyamide obtained bythermal polycondensation of (a) dicarboxylic acid components comprising10 to 80% by mole based on the total carboxylic acid components of1,4-cyclohexanedicarboxylic acid having a specified trans/cis molarratio, and (b) an aliphatic diamine component, and preferably apolyamide wherein a dicarboxylic acid component other than1,4-cyclohexanedicarboxylic acid is an aliphatic dicarboxylic acidhaving 6 to 12 carbon atoms and/or an aromatic dicarboxylic acid and analiphatic diamine component having 4 to 12 carbon atoms.

BEST MODE FOR CARRYING OUT THE INVENTION

[0011] The present invention relates to a polyamide obtained by thermalpolycondensation of dicarboxylic acid components containing1,4-cyclohexanedicarboxylic acid having a specified trans/cis molarratio and a diamine component.

[0012] The polyamide of the present invention is a polymer having amidebonds (—NHCO—) in a main chain thereof. 1,4-Cyclohexanedicarboxylic acidused in the present invention has a trans/cis molar ratio of 50/50 to97/3, preferably 50/50 to 90/10, more preferably 55/45 to 90/10 and mostpreferably 70/30 to 90/10. The trans/cis molar ratio of1,4-cyclohexanedicarboxylic acid can be determined by using1,4-cyclohexanedicarboxylic acid as a raw material of the polyamide byhigh performance liquid chromatography (HPLC). More specifically, it canbe determined by separating 1,4-cyclohexanedicarboxylic acid into transand cis components by a gradient elution method using a reversed-phasecolumn to determine each peak area. In more detail, the polyamide ishydrolyzed with an acid such as hydrobromic acid (HBr), followed bytrimethylsilylation (TMS treatment) and gas chromatography measurementto separate into trans and cis components and determine each peak area.A trans/cis molar ratio of 1,4-cyclohexanedicarboxylic acid lower thanthe above-described 50/50 tends to lower toughness and chemicalresistance of the obtained polyamide. Also, a ratio higher than 97/3tends to deteriorate the appearance of molded articles thereof.

[0013] The dicarboxylic acid component other than1,4-cyclohexanedicarboxylic acid unit preferably used in the presentinvention includes, for example, an aliphatic dicarboxylic acid such asmalonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipicacid, 2-methyladipic acid, trimethyladipic acid, pimelic acid,2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, azelaic acid,sebacic acid, suberic acid, dodecanedicarboxylic acid and eicodionicacid; alicyclic dicarboxylic acid such as 1,3-cyclopentanedicarboxylicacid and 1,3-cyclohexanedicarboxylic acid; and aromatic dicarboxylicacid such as terephthalic acid, isophthalic acid,naphthalenedicarboxylic acid, 2-chloroterephthalic acid,2-methylterephthalic acid, 5-methylisophthalic acid,5-sodiumsulfoisophthalic acid, hexahydroterephthalic acid and diglycolicacid. In the present invention, these dicarboxylic acid components otherthan 1,4-cyclohexanedicarboxylic acid may be used alone or incombination of two or more types thereof. Further, a polyvalentcarboxylic acid having three or more valences, such as trimellitic acid,trimesic acid and pyromellitic acid may be included within a range,which does not deteriorate the object of the present invention. Amongthese dicarboxylic acids, an aliphatic dicarboxylic acid having carbonatoms of 6 to 12 and/or an aromatic dicarboxylic acid is preferable, anduse of adipic acid and/or isophthalic acid is particularly preferable.

[0014] The concentration of 1,4-cyclohexanedicarboxylic acid in thepresent invention is 10 to 80% by mole, preferably 10 to 70% by mole andmost preferably 10 to 60% by mole based on the total dicarboxylic acidcomponents. Among others, a preferable combination of dicarboxylic acidcomponents is 10 to 60% by mole of 1,4-cyclohexanedicarboxylic acid, 20to 90% by mole of adipic acid and 0 to 40% by mole of isophthalic acid,wherein the total of 1,4-cyclohexanedicarboxylic acid, adipic acid andisophthalic acid is 100% by mole. The content of each dicarboxylic acidin the polyamide can be determined for example, by gas chromatography(GC). More specifically, the content can be determined by hydrolyzingthe polyamide with an acid such as hydrobromic acid (HBr), followed bytrimethylsilylation (TMS treatment) and gas chromatography measurementto determine a peak area derived from each component. A content of1,4-cyclohexanedicarboxylic acid in the total dicarboxylic acidcomponents less than 10% by mole tends to lower heat resistance,chemical resistance, light resistance and weather resistance, whereas acontent over 60% by mole tends to deteriorate appearance of moldedarticles thereof.

[0015] An aliphatic diamine components preferably used in the presentinvention includes, for example, aliphatic diamines such asethylenediamine, propylenediamine, tetramethylenediamine,heptamethylenediamine, hexamethylenediamine, pentamethylenediamine,octamethylenediamine, nonamethylenediamine, decamethylenediamine,undecamethylenediamine, dodecamethylenediamine,2-methylpentamethylenediamine, 2,2,4-trimethylhexamethylenediamine,2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine,2,4-dimethyloctamethylenediamine, and 5-methylnonanediamine. Thesealiphatic diamine components may be used alone or in combination of twoor more types thereof. Furthermore, a polyvalent aliphatic diaminecomponent having three or more valences such as bishexamethylenetriaminemay be included within a range, which does not deteriorate the object ofthe present invention. Among these aliphatic diamine components, analiphatic diamine having carbon atoms of 4 to 12 is preferably used anduse of an aliphatic diamine having carbon atoms of 6 to 8 is morepreferable, in particular, use of hexamethylenediamine is mostpreferable.

[0016] In the present invention, besides the above-described1,4-cyclohexanedicarboxylic acid and/or dicarboxylic acid componentsother than 1,4-cyclohexanedicarboxylic acid and diamine components, anypolycondensable amino acid and lactam may be used as a copolymerizationcomponent.

[0017] The amino acid includes, for example, 6-aminocaproic acid,11-aminoundecanoic acid, 12-aminododecanoic acid andp-aminomethylbenzoic acid. In the present invention, these amino acidsmay be used alone or in combination of two or more types thereof.

[0018] The lactam includes, for example, butyrolactam, pivalolactam,caprolactam, capryllactam, enantolactam, undecanolactam anddodecanolactam. In the present invention, these lactams may be usedalone or in combination of two or more types thereof.

[0019] In the present invention, a known end capping agent may be addedto control molecular weight or improve hot water resistance. As the endcapping agent, a monocarboxylic acid or a monoamine is preferable.Furthermore, an acid anhydride such as phthalic anhydride;monoisocyanate; monohalogenated compound; monoesters; and monoalcoholsare included.

[0020] As the monocarboxylic acid which can be used as the end cappingagent, any monocarboxylic acid can be used without specific limitationas long as it has reactivity with an amino group, and the monocarboxylicacid includes, for example, aliphatic monocarboxylic acid such as aceticacid, propionic acid, butyric acid, valeric acid, caproic acid, caprylicacid, lauric acid, tridecylic acid, myristic acid, palmitic acid,stearic acid, pivalic acid and isobutyric acid; alicyclic monocarboxylicacid such as cyclohexanecarboxylic acid; and aromatic monocarboxylicacid such as benzoic acid, toluic acid, α-naphthalene carboxylic acid,β-naphthalene carboxylic acid, methylnaphthalene carboxylic acid andphenylacetic acid. In the present invention, these monocarboxylic acidsmay be used alone or in combination of two or more types thereof.

[0021] As the monoamine which is used as the end capping agent, anymonoamine can be used without specific limitation as long as it hasreactivity with a carboxyl group, and the monoamine includes, forexample, aliphatic monoamine such as methylamine, ethylamine,propylamine, butylamine, hexylamine, octylamine, decylamine,stearylamine, dimethylamine, diethylamine, dipropylamine anddibutylamine; alicyclic monoamines such as cyclohexylamine anddicyclohexylamine; and aromatic monoamines such as aniline, toluidine,diphenylamine and naphthylamine. In the present invention, thesemonoamines may be used alone or in combination of two or more typesthereof.

[0022] As a method of thermal polycondensation of the polyamide used inthe present invention, known methods can be used, and a method ofthermal polycondensation under the condition at a temperature ofpreferably not lower than 100° C., more preferably not lower than 120°C. and most preferably not lower than 170° C. is used. For example, sucha method of thermal melt-polycondensation can be used, where a mixture,a solid salt or an aqueous solution of dicarboxylic acid and diaminesuch as 1,4-cyclohexanedicarboxylic acid and hexamethyleneadipamide isconcentrated by heating at a temperature of 100 to 300° C., while asteam pressure generated is maintained between the normal pressure toabout 5 MPa (in gauge pressure), followed by depressurization at a finalstage to conduct polycondensation under the normal pressure or a reducedpressure. Furthermore, solid phase polymerization method can also beused, where a mixture, a solid salt or a polycondensate of dicarboxylicacid and diamine is subjected to thermal polycondensation at atemperature of not higher than the melting point thereof. These methodsmay be combined if necessary.

[0023] As a polymerization system, batch system or continuous system maybe used. In addition, there is no limitation in polymerization equipmentand known equipment such as an autoclave type reactor, a tumbler typereactor and an extruder type reactor including a kneader can be used.

[0024] Among others, a preferable thermal polycondensation method forobtaining the polyamide of the present invention is as follows. Amixture, a solid salt or an aqueous solution of dicarboxylic acid anddiamine is produced, added thereto with a catalyst or an end cappingagent if necessary, then subjected to thermal polycondensation method at100 to 320° C. to obtain a prepolymer with a number average molecularweight (Mn) of 1,000 to 7,000. The prepolymer is then polymerized insolid phase using a tumbler type reactor or subjected topolycondensation in molten state under a reduced pressure using anextruder type reactor such as a kneader to obtain the polyamide with anumber average molecular weight (Mn) of 7,000 to 100,000.

[0025] When an extruder type reactor such as a kneader is used, anextrusion condition under a reduced pressure of 0 to 0.07 MPa ispreferable. An extrusion temperature is preferably a temperature ofabout 1 to 100° C. above the melting point determined by a measurementwith differential scanning calorimetry (DSC) in accordance with JISK7121. A shear rate is preferably not lower than about 100 (sec⁻¹) andan average residence time is preferably about 1 to 15 minutes. Withinthe above-described ranges, problems such as coloring and failing toachieve a high molecular weight scarcely occur.

[0026] The above-described catalyst is not specifically limited as longas it is known type to be used for polyamide, and includes, for example,phosphoric acid, phosphorous acid, hypophosphorous acid,orthophosphorous acid, pyrophosphorous acid, phenylphosphinic acid,phenylphosphonic acid, 2-methoxyphenylphosphonic acid,2-(2′-pyridil)ethyl-phosphonic acid and metal salts thereof. The metalsalts includes salts of pottassium, sodium, magnesium, vanadium,calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium andantimony, and ammonium salts can also be used. Further, phosphoratessuch as ethyl ester, isopropyl ester, butyl ester, hexyl ester, decylester, isodecyl ester, octadecyl ester, stearyl ester and phenyl estercan also be used.

[0027] The molecular weight of the polyamide of the present invention ispreferably 7,000 to 100,000, more preferably 7,500 to 50,000 and mostpreferably 10,000 to 40,000 in number average molecular weight (Mn) fromthe viewpoint of superior moldability and physical properties. Thenumber average molecular weight (Mn) can be determined by gel permeationchromatography (GPC) using hexafluoroisopropanol as a solvent andpoly(methyl methacrylate) (PMMA) as a standard sample of molecularweight. A polyamide having a number average molecular weight (Mn) of notlower than 7,000 tends to suppress lowering in toughness, and apolyamide having Mn not higher than 100,000 tends to suppress loweringin moldability.

[0028] Furthermore, the polyamide of the present invention has amolecular weight distribution (Mw/Mn), which is a ratio of weightaverage molecular weight (Mw) and number average molecular weight (Mn)determined by the above-described GPC, in a range of preferably 2 to 6,more preferably 2.5 to 5 and most preferably 3 to 4. The molecularweight distribution (Mw/Mn) not less than 2 provides reduced lowering inchemical resistance and the like, while Mw/Mn not higher than 6 providesreduced lowering in moldability and the like.

[0029] Melting point of the polyamide of the present invention ispreferably 210 to 340° C., more preferably 230 to 330° C., further morepreferably 250 to 320° C. and most preferably 260 to 300° C. The meltingpoint can be measured in accordance with JIS K7121. More specifically,it can be determined using, for example, DSC-7 equipment made byPERKIN-ELMER INC. as follows. A 8 mg sample is heated up to 400° C. at aheating rate of 20° C./min, and a peak temperature in the melting curvethus obtained is defined as the melting point. When the melting point isnot lower than 210° C., there is no tendency for lowering the chemicaland heat resistance of the polyamide, while having a melting point nothigher than 340° C. provides less possibility of thermal degradation andthe like during molding.

[0030] Glass transition temperature of the polyamide of the presentinvention is preferably 50 to 110° C., more preferably 50 to 100° C. andmost preferably 50 to 90° C. The glass transition temperature can bemeasured in accordance with JIS K7121. More specifically, it can bedetermined using, for example, DSC-7 equipment made by PERKIN-ELMER INC.as follows. A sample is first melted on “hotstage” (EP80 made by MettlerInc.), followed by quenching and solidifying the molten sample in liquidnitrogen to prepare a measurement sample. The sample of 10 mg is heatedwithin a range from 30 to 300° C. at a heating rate of 20° C./min tomeasure the glass transition point. When the glass transitiontemperature is not lower than 50° C., there is less tendency forlowering the heat and chemical resistance and less possibility of anincrease in the water absorption capacity, whereas a glass transitiontemperature not higher than 110° C. tends to provide better appearancein molding.

[0031] In the present invention, a reinforced polyamide obtained bycompounding inorganic fillers with the polyamide of the presentinvention also gives remarkable effects, which are the object of thepresent invention.

[0032] The inorganic filler for the reinforced polyamide of the presentinvention is not specifically limited, and preferable examples thereofinclude glass fiber, carbon fiber, wollastonite, talc, mica, kaolin,barium sulfate, calcium carbonate, apatite, sodium phosphate, fluorite,silicon nitride, potassium titanate, molybdenum disulfide and apatite.Among others, glass fiber, carbon fiber, wollastonite, talc, mica,kaolin, boron nitride, potassium titanate and apatite are preferablyused from the viewpoint of physical properties, safety and cost.

[0033] Among the above-described glass fiber and carbon fiber, thefibers having a number average fiber diameter of 3 to 30 μm, a weightaverage fiber length of 100 to 750 μm and an aspect ratio (L/D), that isa ratio of weight average fiber length to average fiber diameter, of 10to 100 are most preferably used from the viewpoint of giving thepolyamide superior characteristics. Further, when wollastonite is used,it is most preferred to have a number average fiber diameter of 3 to 30μm, a weight average fiber length of 10 to 500 μm and theabove-described aspect ratio (L/D) of 3 to 100. Moreover, with regard totalc, mica, kaolin, silicon nitride and potassium titanate, those havinga number average fiber diameter of 0.1 to 3 μm are most preferably used.

[0034] In particular, the above-described inorganic fillers of surfacetreated types are preferably used.

[0035] As a surface treatment agent, a coupling agent or a film-formingagent is used.

[0036] The coupling agent includes silane-based coupling agent andtitanium-based coupling agent.

[0037] The silane-based coupling agent includes triethoxysilane,vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane,β-(1,1-epoxycyclohexyl)ethyltrimethoxysilane,N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane,γ-amino-propyltriethoxysilane, N-phenyl-γ-aminopropyl-trimethoxy silane,γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane,γ-aminopropyltrimethoxysilane,γ-aminopropyl-tris(2-methoxy-ethoxy)silane,N-methyl-γ-aminopropyltrimethoxysilane,N-vinylbenzyl-γ-aminopropyltriethoxysilane,triaminopropyltrimethoxysilane, 3-ureidopropyl-trimethoxysilane,3-(4,5-dihydroimidazole)propyl-triethoxysilane, hexamethyldisilazane,N,O-bis(trimethylsilyl)amide and N,N-bis(trimethylsilyl)urea. Amongothers, aminosilane and epoxysilane such asγ-aminopropyl-trimethoxysilane,N-β-(aminoethyl)-γ-aminopropyl-trimethoxysilane,γ-glycidoxypropyl-trimethoxysilane,β-(1,1-epoxycyclohexyl)ethyltrimethoxysilane and the like are preferablyused due to economical advantage and easy handling.

[0038] The titanium-based coupling agent includesisopropyltriisostearoyl titanate, isopropyltridecylbenzeneslufonyltitanate, isopropyltris(dioctylpyrophosphate) titanate,tetraisopropylbis(dioctylphosphite) titanate,tetraoctylbis(ditridecylphosphite) titanate,tetra(1,1-diallyloxymethyl-1-butyl)bis(ditridecyl-phosphite)titanate,bis(dioctylpyrophophate)oxyacetate-titanate,bis(dioctylpyrophophate)ethylene titanate, isopropyltrioctanoyltitanate, isopropyldimethacrylisosteraoyl titanate,isopropylisostearoyldiacryl titanate, isopropyltri(dioctylphosphate)titanate, isopropyltricumylphenyl titanate,isopropyltri(N-amidoethylaminoethyl) titanate, dicumylphenyloxyacetatetitanate and diisostearoyl-ethylene titanate and the like.

[0039] The film forming agent includes polymers such as urethane typepolymers, acrylic acid-based polymers, copolymers of maleic anhydrideand an unsaturated monomer such as ethylene, styrene, α-methylstyrene,butadiene, isoprene, chloroprene, 2,3-dichlorobutadiene, 1,3-pentadieneand cyclooctadiene, epoxy polymers, polyester polymers, vinylacetate-based polymers and polyether polymers. Among others, inparticular, urethane polymers, acrylic acid-based polymers andcopolymers of maleic anhydride and butadiene, ethylene and styrene andmixtures thereof are preferably used from the viewpoints of economicaladvantage and superior performances.

[0040] The inorganic fillers may be surface treated using theabove-described coupling agents and film forming agents by well knownmethods including sizing treatment in which a solution or a suspensionof the above-described coupling agent and film forming agent in anorganic solvent is surface-coated as a sizing agent, dry mixing methodfor coating the same using a Henschel mixer, super mixer, Laydy mixer ortwin-cylinder mixer and spray method for spray coating the same as wellas integral blend method and dry concentrate method. A combined methodthereof may also be included, for example, coating of a coupling agentand a part of a film forming agent by sizing treatment followed byspraying the remainder of the film forming agent. Among them, inparticular, sizing treatment, dry mixing, spraying method and a combinedmethod thereof are preferably used from the viewpoint of economicaladvantage.

[0041] The method for producing the above-described reinforced polyamideis not specifically limited as long as it is a mixing method for thepolyamide of the present invention and inorganic fillers. For example,the melt mixing temperature is preferably about 250 to 350° C. as aresin temperature and the melt mixing time is preferably about 1 to 30minutes. Further, the feeding method for the components of thereinforced polyamide into a melt mixing equipment may be a simultaneousfeed system of all components into the same feeding port or a method tofeed each component from different feeding ports, respectively. Morespecifically, the mixing method includes, for example, a method formixing the polyamide and inorganic fillers using a Henschel mixer andthe like, followed by feeding them into a melt mixing equipment tocomplete kneading, or a method for compounding inorganic fillers from aside feeder into the polyamide in molten state in a single screw or atwin screw extruder.

[0042] As the melt mixing equipment, known equipment can be used. Forexample, single screw or twin screw extruder, Banbury mixer and mixingroll are preferably used.

[0043] The number average fiber diameter and weight average fiber lengthof the inorganic fillers can be determined by dissolving the moldedarticle in a solvent for the polyamide such as formic acid, optionallyselecting 100 or more fibers of inorganic fillers from the insolublecomponents, and examining them using an optical microscope or a scanningelectron microscope.

[0044] The amount of inorganic fillers to be compounded is 5 to 500parts by weight, preferably 10 to 250 parts by weight and morepreferably 10 to 150 parts by weight based on 100 parts by weight of thepolyamide. A compounding amount not less than 5 parts by weight providessufficiently improved mechanical properties, while a compounding amountnot higher than 500 parts by weight provides less lowering inmoldability.

[0045] In the polyamide or the reinforced polyamide of the presentinvention, other resins may be mixed, if necessary, within a range thatdoes not deteriorate the object of the present invention. Said otherresin to be compounded is preferably a thermoplastic resin and a rubbercomponent.

[0046] The above-described thermoplastic resin includes, for example,polystyrenic resins such as atactic polystyrene, isotactic polystyrene,syndiotactic polystyrene, AS resin and ABS resin; polyester resins suchas poly(ethylene terephthalate) and poly(butylene terephthalate);polyamide such as nylon 6, 66, 612 and 66/6I; polyether resins such aspolycarbonate, polyphenylene ether, polysulfone and polyethersulfone;condensation resins such as poly(phenylene sulfide) andpolyoxymethylene; acrylic resins such as poly(acrylic acid),polyacrylate and poly(methyl methacrylate); polyolefinic resins such aspolyethylene, polypropylene, polybutene and ethylene-propylenecopolymer; halogen containing resins such as poly(vinyl chloride) andpoly(vinylidene chloride); phenol resin; and epoxy resin.

[0047] The rubber component includes, for example, natural rubber,polybutadiene, polyisoprene, polyisobutylene, Neoprene, polysulfiderubber, thiokol rubber, acrylic rubber, urethane rubber, siliconerubber, epichlorohydrin rubber, styrene-butadiene block copolymer (SBR),hydrogenated styrene-butadiene block copolymer (SEB),styrene-butadiene-styrene block copolymer (SBS), hydrogenatedstyrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene blockcopolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP),styrene-isoprene-styrene block copolymer (SIS), hydrogenatedstyrene-isoprene-styrene block copolymer (SEPS), styrene-butadienerandom copolymer, hydrogenated styrene-butadiene random copolymer,styrene-ethylene-propylene random copolymer, styrene-ethylene-butylenerandom copolymer, ethylene-propylene copolymer (EPR),ethylene-(1-butene)copolymer, ethylene-(1-hexene) copolymer,ethylene-(1-octene)copolymer and ethylene-propylenediene copolymer(EPDM); and core-shell type of rubber such asbutadiene-acrylonitrile-styrene core-shell rubber (ABS), methylmethacrylate-butadiene-styrene core-shell rubber (MBS), methylmethacrylate-butyl acrylate-styrene core-shell rubber (MAS), octylacrylate-butadiene-styrene core-shell rubber (MABS), alkylacrylate-butadiene-acrylonitrile-styrene core-shell rubber (AABS),butadiene-styrene core-shell rubber (SBR) and siloxane containing rubbersuch as methyl methacrylate-butyl acrylatesiloxane.

[0048] Modified forms of the above-described other resins and rubbercomponents are also preferably used. The modified form means theabove-described other resin and rubber component is modified with amodifier having a polar group, and includes, for example, polypropylenemodified with maleic anhydride, polyphenylene ether modified with maleicanhydride, polypropylene modified with maleic anhydride, SEBS modifiedwith maleic anhydride, SEPS modified with maleic anhydride,ethylene-propylene copolymer modified with maleic anhydride,ethylene-(1-butene) copolymer modified with maleic anhydride,ethylene-(1-hexene) copolymer modified with maleic anhydride,ethylene-(1-octene) copolymer modified with maleic anhydride, EPDMmodified with maleic anhydride, SEBS modified with epoxy group,ethylene-propylene copolymer modified with epoxy group,ethylene-(1-butene) copolymer modified with epoxy group,ethylene-(1-hexene) copolymer modified with epoxy group andethylene-(1-octene) copolymer modified with epoxy group. These otherresin and rubber component and modified forms thereof may be compoundedalone or in combination of two or more types thereof.

[0049] Various additives used for usual polyamide resins can be added,if necessary, within a range not to impair the object of the presentinvention. The additives include, for example, flame retardant such asantimony trioxide, aluminum hydroxide, magnesium hydroxide, zinc borate,zinc stannate, zinc hydroxystannate, ammonium polyphosphate, cyanuricmelamine, succinoguanamine, melamine polyphosphate, melamine sulfate,melamine phthalate, aromatic polyphosphates and composite glass powder;pigment or colorant such as titanium white and carbon black;phosphite-based stabilizer such as phosphite esters; heat stabilizersuch as hindered phenol and hindered amine; heat resistance improvingagent such as cuprous iodide and potassium iodide; moldability improvingagent such as calcium stearate, calcium montanate, stearyl stearate anderucic acid amide; plasticizers; weather resistance improving agent; andantistatic agent.

[0050] Molded articles of the polyamide of the present invention orcomposition thereof can be obtained using commonly known plastic moldingmethods, such as compression molding, injection molding, gas assistedinjection molding, welding, extrusion, blow molding, film forming,hollow molding, multi-layer molding and melt spinning.

[0051] The molded article of the present invention can also be usedpreferably as a molded body with a coated film on the surface thereofdue to superior surface appearance. Any coating method can be suitablyused without specific limitation as long as it is a known method. Themethod includes, for example, a spray method and electrostatic coatingmethod. Further, any coating material can be suitably used withoutspecific limitation as long as it is a known material, including coatingmaterials such as melamine-curable polyester-polyol resin type andacryl-urethane type.

[0052] The molded articles of the polyamide of the present invention orcompound thereof are superior in heat resistance, light resistance andweather resistance, as well as superior in toughness, low waterabsorption, chemical resistance and appearance. Therefore, it isexpected to be suitably used in industrial machinery parts such as agear and cam; electric/electronics parts such as a connector, switch,relay, MID, printed circuit board and housing for electronics parts; andextrusion applications such as a film, sheet, filament, tube, rod andblow molded articles. It is also expected to be suitably used asautomotive parts such as interior parts/outer/panels/exterior parts,under-hood parts and electric equipment parts.

[0053] Hereinbelow, the present invention will be described in moredetail using Examples, but it should not be construed to be limited bythe following Examples as long as the gist of the present invention ismaintained. Physical properties shown in the following Examples andComparative Examples were evaluated as follows.

[0054] (1) Trans/Cis Molar Ratio of 1,4-cyclohexanedicarboxylic Acid

[0055] HPLC (high performance liquid chromatography) equipment (LC-10Amade by Shimadzu Corp.) was used. 1,4-Cyclohexanedicarboxylic acidmonomer was separated into a trans component (elution time of about 11minutes) and a cis component (elution time of about 14.5 minutes) by agradient elution method using reversed-phase column, and thus said ratiowas determined from a ratio of area of each peak. Detailed conditions ofHPLC analysis are as follows: Equipment: LC-10A vp made by ShimadzuCorp.; Reversed-phase Develosil PRAQUOUS made by Nomura (C30) column:Chemical Co. Ltd.; Temperature: 40° C.; Flow rate: 1.0 ml/min;Detection: UV 214 nm; Mobile phase A: Water [0.1% by weight oftrifluoroacetic acid (TFA)]; Mobile phase B: Water/acetonitrile = 10/90parts by weight, [0.1% by weight of trifluoroacetic acid (TFA)]; Mixingratio of B = 0 → 100% (over 15 minutes); mobile phases: Sampleconcentration: 10 mg/ml, solvent: water/acetonitrile = 50/50); Injectionvolume 20 ml. of sample solution:

[0056] (2) Characteristics of the Polyamide

[0057] (2-1) Number Average Molecular Weight (Mn) and Molecular WeightDistribution (Mw/Mn)

[0058] These characteristics were determined by gel permeationchromatography (GPC) using the polyamide or molded articles thereofunder the following conditions. Equipment: HLC-8020 made by TOSOH CORP.;Detector: Differential refractive index meter (RI); Solvent:Hexafluoroisopropanol dissolving 0.1% by mole of sodiumtrifluoroacetate; Column: Two TSKgel-GMHHR-H and one G1000HHR made byTOSOH CORP.; Solvent flow rate: 0.6 ml/min; Sample 1 to 3 (mg sample)/1(ml solvent). concentration:

[0059] Insoluble components were removed by filtration to preparemeasurement samples. Number average molecular weight (Mn) and weightaverage molecular weight (Mw) were determined based on elution curveobtained by using polymethyl methacrylate as a standard sample. Thevalue of (Mw/Mn) was calculate by dividing Mw by Mn.

[0060] (2-2) Specific Gravity (Kg/m³)

[0061] Specific gravity of an injection molded test piece was measuredusing the specific gravity measuring equipment (SD-120L made by MIRAQE).

[0062] (2-3) Melting Point (° C.), Heat of Melting (J/g) andCrystallization Temperature (° C.)

[0063] These properties were measured in accordance with JIS K7121 andK7122 using Model DSC-7 made by PERKIN-ELMER INC. Measurement wasconducted according to the following procedure: A sample of about 10 mgwas heated at a heating rate of 20° C./min under nitrogen atmosphere toobtain an endothermic peak (melting peak), which was defined as Tm¹ (°C.). The sample was kept in a melt state at a temperature of Tm¹+40° C.for 2 minutes, then cooled down to 30° C. at a cooling rate of 20°C./min to obtain an exothermic peak (crystallization peak), which wasdefined as crystallization temperature. Subsequently, the sample waskept at 30° C. for 2 minutes, followed by heating at a heating rate of20° C./min to obtain a peak (melting peak), which was defined as meltingpoint Tm² (° C.). Heat of melting was determined from a peak areathereof.

[0064] (2-4) Glass Transition Temperature (° C.)

[0065] Glass transition temperature was measured in accordance with JISK7121 using Model DSC-7 made by PERKIN-ELMER INC. A sample was firstmelted on a hot stage (EP80 made by Mettler Inc.), then the sample inmolten state was quenched and solidified in liquid nitrogen to prepare ameasurement sample. Glass transition temperature was measured by heating10 mg of the sample in a range from 30 to 300° C. at a heating rate of20° C./min.

[0066] (2-5) Water Absorption Ratio (% by Weight)

[0067] Water absorption ratio was determined by measuring weights beforeand after immersing a sample in water at 23° C. for 24 hours. Morespecifically, water absorption ratio was obtained by dividing a weightincrease after the immersion by a weight of the sample in an absolutedry condition.

[0068] (3) Preparation of Molded Article and Physical Properties Thereof

[0069] Molded article was prepared using injection molding machine,PS40E made by Nissei Plastic Ind. Co., Ltd. Molded article was obtainedunder the following injection molding conditions: Mold temperature: 120°C.; injection time: 17 seconds; cooling time: 20 seconds. Cylindertemperature was set at a temperature of about 30° C. above the meltingpoint of the polyamide determined in accordance with the above-describedprocedure (1-1).

[0070] (4) Mechanical Properties of the Polyamide

[0071] (4-1) Tensile Strength (MPa) and Tensile Elongation (%)

[0072] These properties were measured in accordance with ASTM D638.

[0073] (4-2) Flexural Modulus (GPa)

[0074] This property was measured in accordance with ASTM D790.

[0075] (4-3) Notched Izod Impact Strength (J/m)

[0076] This property was measured in accordance with ASTM D256.

[0077] (4-4) Heat Deflection Temperature (° C.)

[0078] This property was measured in accordance with ASTM D648 under aload of 1.86 MPa.

[0079] (4-5) Chemical Resistance

[0080] Chemical resistance was evaluated by measuring a depth of crackafter a treatment with calcium chloride. More specifically, adumbbell-shaped injection molded test piece (3 mm thick) was immersed inwater at 80° C. for 8 hours, then weights were hung down at both endsthereof so that stress of 19.6 MPa was loaded at the support point(which was apart by 10 cm from the weight-hanging ends). Further, agauze of 74 mm×74 mm was attached on the support area (after folded twotimes to a rectangular shape of 37 mm×18 mm), on which 1 ml of 30% byweight of calcium chloride aqueous solution was dropped. The test piecewas placed in an oven (100° C.) for 2 hours, then a depth of theresulting crack on the test piece was measured.

[0081] (4-6) Light Resistance

[0082] Light resistance was evaluated by calculating retention (%) fromtensile strengths before and after irradiation of UV light of awavelength of 254 nm for 1 hour at a distance of 1 mm from the surfaceof dumbbell-shaped injection molded test piece for tensile strengthmeasurement.

[0083] (4-7) Surface Appearance

[0084] Surface appearance was evaluated by measuring Gs 60° C. inaccordance with JIS-K7150 using a handy gloss meter IG320 made by HoribaLtd.

EXAMPLE 1

[0085] In 3,000 ml of distilled water, 500.4 g (2.906 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of80/20, 637.4 g (4.360 mole) of adipic acid and 844.3 g (7.266 mole) ofhexamethylenediamine were dissolved to prepare an aqueous solution witha neutralization equivalent point of pH=7.80 at 60° C. The aqueoussolution was charged in a 6L autoclave, which was purged with nitrogen.The solution was then concentrated, while stirred at 110 to 150° C., bygradually removing steam until the concentration of the solution reached70% by weight. Then the temperature was raised to 218° C. and pressurewas raised to 22 Kg/cm² in the autoclave. Reaction was continued for 1additional hour until the temperature reached 253° C., while thepressure was maintained at 22 Kg/cm² by gradually removing steam toobtain a prepolymer with a number average molecular weight (Mn) of5,000. This prepolymer was crushed to pieces having a size not largerthan 3 mm and dried at 100° C. for 24 hours, under nitrogen gas streamat a flow rate of 20 L/min. Subsequently, the prepolymer was subjectedto solid phase polymerization at 210° C. for 10 hours under nitrogen gasstream at a flow rate of 200 ml/min to obtain a polyamide. Resultsobtained are shown in Table 1.

EXAMPLE 2

[0086] A polyamide was polymerized and molded according to the samemethod as in Example 1 except that 1,4-cyclohexanedicarboxylic acidhaving a trans/cis molar ratio of 65/35 was used. Results obtained areshown in Table 1.

EXAMPLE 3

[0087] A polyamide was polymerized and molded according to the samemethod as in Example 1 except that 1,4-cyclohexanedicarboxylic acidhaving a trans/cis molar ratio of 55/45 was used. Results obtained areshown in Table 1.

EXAMPLE 4

[0088] A polyamide was polymerized and molded according to the samemethod as in Example 1 except that 1,4-cyclohexanedicarboxylic acidhaving a trans/cis molar ratio of 95/5 was used. Results obtained areshown in Table 1.

COMPARATIVE EXAMPLE 1

[0089] A polyamide was polymerized and molded according to the samemethod as in Example 1 except that 1,4-cyclohexanedicarboxylic acidhaving a trans/cis molar ratio of 20/80 was used. Results obtained areshown in Table 1.

COMPARATIVE EXAMPLE 2

[0090] A polyamide was polymerized and molded according to the samemethod as in Example 1 except that 1,4-cyclohexanedicarboxylic acidhaving a trans/cis molar ratio of 99.7/0.3 was used. Results obtainedare shown in Table 1.

EXAMPLE 5

[0091] A polyamide was polymerized and molded according to the samemethod as in Example 1 except that 750.8 g (4.360 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of80/20, 424.9 g (2.906 mole) of adipic acid and 844.3 g (7.266 mole) ofhexamethylenediamine were used. Results obtained are shown in Table 2.

EXAMPLE 6

[0092] A polyamide was polymerized and molded according to the samemethod as in Example 1 except that 187.7 g (1.090 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of80/20, 902.9 g (6.176 mole) of adipic acid and 844.3 g (7.266 mole) ofhexamethylenediamine were used. Results obtained are shown in Table 2.

COMPARATIVE EXAMPLE 3

[0093] A polyamide was polymerized according to the same method as inExample 1 except that 1363.8 g (7.266 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of 80/20and 844.3 g (7.266 mole) of hexamethylenediamine were used. Meltingpoint was measured in accordance with the method described in (2-3). Tm¹was 412° C. but Tm² was not detected. The sample could not be moldedbecause Tm¹ was over 400° C.

COMPARATIVE EXAMPLE 4

[0094] A polyamide was polymerized and molded according to the samemethod as in Example 1 except that 62.6 g (0.363 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of80/20, 1,009.1 g (6.903 mole) of adipic acid and 844.3 g (7.266 mole) ofhexamethylenediamine were used. Results obtained are shown in Table 2.

EXAMPLE 7

[0095] In 3,000 ml of distilled water, 1,251.2 g (7.266 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of 80/20and 1,048.2 g (7.266 mole) of octamethylenediamine were dissolved toprepare an aqueous solution with a neutralization equivalent point ofpH=7.80 at 60° C. The solution was charged in a 6L autoclave, which waspurged with nitrogen. The solution was then concentrated, while beingstirred at 110 to 150° C., by gradually removing steam until theconcentration of the solution reached 70% by weight. Then thetemperature was raised to 218° C. and pressure was raised to 22 Kg/cm²in the autoclave. The reaction was continued for 1 additional hour untilthe temperature reached 253° C., while the pressure was maintained at 22Kg/cm² by gradually removing steam to obtain a prepolymer with a numberaverage molecular weight (Mn) of 5,000. This prepolymer was crushed topieces having a size not larger than 3 mm and dried at 100° C. for 24hours, under nitrogen gas stream at a flow rate of 20 L/min. The driedprepolymer was extruded using a kneader type reaction extruder (BT-30made by Plastic Engineering Institute Co. Ltd.) under the conditions of300° C., reduced pressure of 0.03 MPa and residence time of 10 minutesto obtain a polyamide. Results obtained are shown in Table 3.

EXAMPLE 8

[0096] A polyamide was polymerized and molded according to the samemethod as in Example 7 except that 1,150.1 g (7.266 mol) ofnonamethylenediamine was used instead of octamethylenediamine in Example7. Results obtained are shown in Table 3.

EXAMPLE 9

[0097] A polyamide was polymerized and molded according to the samemethod as in Example 7 except that 1,455.9 g (7.266 mol) ofdodecamethylenediamine was used instead of octamethylenediamine inExample 7. Results obtained are shown in Table 3.

EXAMPLE 10

[0098] In 3,000 ml of distilled water, 250.2 g (1.453 mole) of1,4-cyclohexanedicarboxylic acid which has a trans/cis molar ratio of80/20, 849.8 g (5.813 mole) of adipic acid and 1,354.4 g (7.266 mole) ofundecamethylenediamine were dissolved at 60° C. to prepare an aqueoussolution. A polyamide was polymerized and molded using this aqueoussolution according to the same method as in Example 7. Results obtainedare shown in Table 3.

COMPARATIVE EXAMPLE 5

[0099] A polyamide was polymerized and molded according to the samemethod as in Example 7 except that 1,363.8 g (7.266 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of 20/80was used. Results obtained are shown in Table 4.

COMPARATIVE EXAMPLE 6

[0100] In 2,688 ml of distilled water, 1,251.2 g (7.266 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of 50/50and 1,354.4 g (7.266 mole) of undecamethylenediamine were dissolved at60° C. to prepare an aqueous solution. A polyamide was polymerized andmolded according to the same method as in Example 7 except that thisaqueous solution was used. Results obtained are shown in Table 4.

COMPARATIVE EXAMPLE 7

[0101] In 2,688 ml of distilled water, 1,063.5 g (6.176 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of20/80, 159.3 g (1.090 mole) of adipic acid and 1,354.4 g (7.266 mole) ofundecamethylenediamine were dissolved at 60° C. to prepare an aqueoussolution. A polyamide was polymerized and molded according to the samemethod as in Example 7 except that this aqueous solution was used.Results obtained are shown in Table 4.

EXAMPLE 11

[0102] In 2,731 ml of distilled water, 132.4 g (0.769 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of80/20, 1,206.3 g (8.254 mole) of adipic acid, 132.4 g (0.797 mole) ofisophthalic acid and 1,141.1 g (9.820 mole) of hexamethylenediamine weredissolved to prepare an aqueous solution with a neutralizationequivalent point of pH=7.56 at 60° C. The aqueous solution was chargedin a 6L autoclave, which was purged with nitrogen. The solution was thenconcentrated, while being stirred at 110 to 150° C., by graduallyremoving steam until the concentration of the solution reached 70% byweight. Then the temperature was raised to 218° C. and pressure wasraised to 18 Kg/cm² in the autoclave. The reaction was continued for 1additional hour until the temperature reached 253° C., while thepressure was maintained at 18 Kg/cm² by gradually removing steam. Thenthe pressure was lowered to 1 Kg/cm² over 1 hour and the polymerizationwas continued for 15 additional minutes while nitrogen gas was made toflow in the autoclave to obtain a polyamide. This polyamide was crushedto pieces having a size not larger than 2 mm, and dried at 100° C. for12 hours under the nitrogen atmosphere. Results obtained are shown inTable 4.

EXAMPLE 12

[0103] A polyamide was polymerized and molded according to the samemethod as in Example 11 except that 1,4-cyclohexanedicarboxylic acidhaving a trans/cis molar ratio of 60/40 was used. Results obtained areshown in Table 5.

EXAMPLE 13

[0104] In 2,688 ml of distilled water, 220.7 g (1.282 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of80/20, 1.029.9 g (7.047 mole) of adipic acid, 220.7 g (1.328 mole) ofisophthalic acid and 1,122.1 g (9.657 mole) of hexamethylenediamine weredissolved to prepare an aqueous solution with a neutralizationequivalent point of pH=7.56 at 60° C. A polyamide was polymerized andmolded according to the same method as in Example 11 except that thisaqueous solution was used. Results obtained are shown in Table 5.

EXAMPLE 14

[0105] In 2,688 ml of distilled water, 498.9 g (2.897 mole) of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of80/20, 564.6 g (3.863 mole) of adipic acid, 481.5 g (2.897 mole) ofisophthalic acid and 1,122.1 g (9.657 mole) of hexamethylenediamine weredissolved to prepare an aqueous solution with a neutralizationequivalent point of pH=7.56 at 60° C. A polyamide was polymerized andmolded according to the same method as in Example 11 except that thisaqueous solution was used. Results obtained are shown in Table 5.

COMPARATIVE EXAMPLE 8

[0106] A polyamide was polymerized and molded according to the samemethod as in Example 11 except that 1,4-cyclohexanedicarboxylic acidhaving a trans/cis molar ratio of 99.7/0.3 was used. Results obtainedare shown in Table 6.

COMPARATIVE EXAMPLE 9

[0107] A polyamide was polymerized and molded according to the samemethod as in Example 11 except that 1,4-cyclohexanedicarboxylic acidhaving a trans/cis molar ratio of 45/55 was used. Results obtained areshown in Table 6.

COMPARATIVE EXAMPLE 10

[0108] In 2,800 ml of distilled water, 132.4 g (0.797 mole) ofterephthalic acid, 1,206.3 g (8.254 mole) of adipic acid, 132.4 g (0.797mole) of isophthalic acid and 1,144.4 g (9.848 mole) ofhexamethylenediamine were dissolved to prepare an aqueous solution witha neutralization equivalent point of pH=7.17 at 60° C. A polyamide waspolymerized and molded according to the same method as in Example 11except that this aqueous solution was used. Results obtained are shownin Table 6.

COMPARATIVE EXAMPLE 11

[0109] In 2,616 ml of distilled water, 1,206.3 g (8.254 mole) of adipicacid, 264.8 g (1.594 mole) of isophthalic acid and 1,144.4 g (9.848mole) of hexamethylenediamine were dissolved to prepare an aqueoussolution with a neutralization equivalent point of pH=7.15 at 60° C. Apolyamide was polymerized and molded according to the same method as inExample 11 except that this aqueous solution was used. Results obtainedare shown in Table 6.

EXAMPLE 15

[0110] Using 100 parts by weight of the polyamide obtained in Example 1and 40 parts by weight of glass fiber with a diameter of 10 μm and anaverage length of 3 mm (ECS03T275 GH made by Nippon Electric Glass Co.,Ltd.), dry blend was carried out. This blend was melt mixed andpelletized using a co-rotating twin screw extruder TEM35 (L1/D1=47) madeby Toshiba Machine Co., Ltd., under conditions of cylindertemperature=320° C. and revolution speed=400 rpm to produce a polyamidecomposition. Results obtained are shown in Table 7.

EXAMPLE 16

[0111] A composition was prepared by compounding glass fiber into apolyamide according to the same method as in Example 14 except that thepolyamide obtained in Example 11 was used, then injection molding of thecomposition was carried out. Results obtained are shown in Table 7.

EXAMPLE 17

[0112] Using 100 parts by weight of the polyamide obtained in Example 1,30 parts by weight of glass fiber with a diameter of 10 μm and anaverage length of 3 mm (ECS03T275 GH made by Nippon Electric Glass Co.,Ltd.) and 10 parts by weight of wollastonite (NYGLOS5: surface treatedtype with a diaminosilane coupling agent, having an average fiberdiameter of 5 μm and an average fiber length of 65 μm made by TomoeEngineering Co., Ltd.), dry blend was carried out. This blend was meltmixed and pelletized using a co-rotating twin screw extruder TEM35(L1/D1=47) made by Toshiba Machine Co., Ltd., under conditions ofcylinder temperature=320° C. and revolution speed=400 rpm to produce apolyamide composition. Results obtained are shown in Table 7.

EXAMPLE 18

[0113] Using 100 parts by weight of the polyamide obtained in Example 1,30 parts by weight of glass fiber with a diameter of 10 μm and anaverage length of 3 mm (ECS03T275 GH made by Nippon Electric Glass Co.,Ltd.) and 10 parts by weight of mica (A-11 with an average particle sizeof 3 μm supplied by TSUCHIYA KAOLIN IND. LTD.), dry blend was carriedout. This blend was melt mixed and pelletized using a co-rotating twinscrew extruder TEM35 (L1/D1=47) made by Toshiba Machine Co., Ltd., underconditions of cylinder temperature=320 to 350° C. and revolutionspeed=400 rpm to produce a polyamide composition. Results obtained areshown in Table 7.

COMPARATIVE EXAMPLE 12

[0114] A composition was prepared by compounding glass fiber into apolyamide according to the same method as in Example 14 except that thepolyamide obtained in Comparative Example 1 was used, then injectionmolding of the composition was carried out. Results obtained are shownin Table 7. TABLE 1 Comparative Comparative Example 1 Example 2 Example3 Example 4 Example 1 Example 2 Characteristics of Monomer DicarboxylicAcid Component ADA/CHDC ADA/CHDC ADA/CHDC ADA/CHDC ADA/CHDC ADA/CHDC (%by mole) (60/40) (60/40) (60/40) (60/40) (60/40) (60/40) Trans/Cis MolarRatio of CHDA 80/20 65/35 55/45 95/5 20/80 99.7/0.3 Diamine Component (%by mole) C6DA (100) C6DA (100) C6DA (100) C6DA (100) C6DA (100) C6DA(100) Characteristics of Polymer Melting Point: Tm² (° C.) 290 290 289291 288 293 Melting Enthalpy (J/g) 25 25 25 25 24 26 CrystallizationTemperature (° C.) 248 248 248 250 246 255 Glass Transition Temperature(° C.) 70 70 70 72 68 75 Number Average Molecular Weight 15,500 15,50015,000 15,000 15,000 14,500 (Mn) Molecular Weight Distribution 2.9 2.92.9 3.0 3.0 3.2 (Mw/Mn) Specific Gravity (Kg/m³) 1.12 1.12 1.12 1.121.12 1.12 Mechanical Properties of Polymer Tensile Strength (MPa) 85 8585 85 78 85 Tensile Elongation (%) 20 18 16 20 7 20 Flexural Modulus(Gpa) 2.9 2.9 2.9 2.9 2.8 2.9 Notched Izod Impact Strength 55 55 50 5547 55 (J/m) Heat Deflection Temperature 100 100 98 100 97 100 (° C.)Water Absorption Ratio 0.80 0.75 0.75 0.85 0.75 0.95 (% by weight)Retension of Strength after >95 >95 >95 >95 >95 >95 UV Irradiation (%)Depth of Crack after CaCl₂ 0.5 0.5 0.6 0.5 2.7 0.5 Treatment (μm)Appearance (Gloss at 60° C.) 75 75 75 70 77 50

[0115] TABLE 2 Compara- Comparative tive Example 5 Example 6 Example 3Example 4 Characteristics of Monomer Dicarboxylic Acid ADA/ ADA/ CHDCADA/ Component CHDC CHDC (100) CHDC (% by mole) (40/60) (85/15) (95/5)Trans/Cis Molar Ratio 80/20 80/20 80/20 80/20 of CHDA Diamine ComponentC6DA C6DA C6DA C6DA (% by mole) (100) (100) (100) (100) Characteristicsof Polymer Melting Point: 327 283 (Tm1 = 412) 270 Tm² (° C.) MeltingEnthalpy (J/g) 11 46 ND* 50 Crystallization 289 241 ND⁺ 225 Temperature(° C.) Glass Transition 90 55 ND⁺ 50 Temperature (° C.) Number Average15,000 14,500 13,000 16,500 Molecular Weight (Mn) Molecular Weight 3.03.0 3.0 3.0 Distribution (Mw/Mn) Specific Gravity 1.12 1.13 1.11 1.14(Kg/m³) Mechanical Properties of Polymer Tensile Strength 82 85 not 82(MPa) moldable Tensile Elongation (%) 11 25 25 Flexural Modulus 2.8 2.92.8 (Gpa) Notched Izod Impact 47 55 55 Strength (J/m) Heat Deflection120 87 not 79 Temperature (° C.) moldable Water Absorption 0.83 0.951.23 Ratio (% by weight) Retension of Strength >95 >95 >95 after UVIrradiation (%) Depth of Crack after no crack 1.8 >5 CaCl₂ Treatment(μm) Appearance 70 75 77 (Gloss at 60° C.)

[0116] TABLE 3 Example 7 Example 8 Example 9 Example 10 Characteristicsof Monomer Dicarboxylic Acid CHDC CHDC CHDC CHDC/ADA Component (100)(100) (100) (20/80) (% by mole) Trans/Cis Molar Ratio 80/20 80/20 80/2080/20 of CHDA Diamine Component C8DA C9DA C12DA C11DA (% by mole) (100)(100) (100) (100) Characteristics of Polymer Melting Point: 325 313 285262 Tm² (° C.) Melting Enthalpy (J/g) 11 18 25 22 Crystallization 276271 232 215 Temperature (° C.) Glass Transition 86 76 57 52 Temperature(° C.) Number Average 15,500 15,500 15,000 15,000 Molecular Weight (Mn)Molecular Weight 3.5 3.5 3.6 3.4 Distribution (Mw/Mn) Specific Gravity1.09 1.09 1.09 1.11 (Kg/m³) Mechanical Properties of Polymer TensileStrength 85 85 85 85 (MPa) Tensile Elongation (%) 12 18 25 22 FlexuralModulus 2.8 2.8 2.8 2.8 (Gpa) Notched Izod Impact 45 55 55 55 Strength(J/m) Heat Deflection 113 98 81 75 Temperature (° C.) Water Absorption0.53 0.52 0.50 0.65 Ratio (% by weight) Retension ofStrength >95 >95 >95 >95 after UV Irradiation (%) Depth of Crack afterno crack no crack no crack no crack CaCl₂ Treatment (μm) Appearance 7077 77 77 (Gloss at 60° C.)

[0117] TABLE 4 Comparative Comparative Comparative Example 5 Example 6Example 7 Characteristics of Monomer Dicarboxylic Acid Component CHDCCHDC ADA/CHDC (% by mole) (100) (100) (15/85) Trans/Cis Molar Ratio of20/80 50/50 20/80 CHDA Diamine Component C8DA (100) C11DA C11DA (% bymole) (100) (100) Characteristics of Polymer Melting Point: Tm² (° C.)323 282 267 Melting Enthalpy (J/g) 10 22 25 Crystallization Temperature275 239 225 (° C.) Glass Transition Temperature 85 75 55 (° C.) NumberAverage Molecular 15,000 14,500 14,500 Weight (Mn) Molecular Weight 3.53.7 3.5 Distribution (Mw/Mn) Specific Gravity (Kg/m³) 1.09 1.09 1.09Mechanical Properties of Polymer Tensile Strength (MPa) 75 85 85 TensileElongation (%) 5 8 11 Flexural Modulus (Gpa) 2.8 2.8 2.8 Notched IzodImpact Strength 35 40 50 (J/m) Heat Deflection Temperature 110 100 78 (°C.) Water Absorption Ratio 0.55 0.5 0.5 (% by weight) Retension ofStrength after >95 >95 >95 UV Irradiation (%) Depth of Crack after CaCl₂no crack no crack no crack Treatment (μm) Appearance (Gloss at 60° C.)70 45 60

[0118] TABLE 5 Example Example Example Example 11 12 13 14Characteristics of Monomer Dicarboxylic Acid ADA/ ADA/ ADA/ ADA/Component (% by mole) CHDC/ CHDC/ CHDC/ CHDC/ IPA IPA IPA IPA (84/8/8)(84/8/8) (73/13/14) (40/30/30) Trans/Cis Molar Ratio of 80/20 60/4080/20 80/20 CHDA Diamine Component C6DA C6DA C6DA C6DA (% by mole) (100)(100) (100) (100) Characteristics of Polymer Melting Point: 257 257 250242 Tm² (° C.) Melting Enthalpy (J/g) 36 36 28 22 Crystallization 217217 212 199 Temperature (° C.) Glass Transition 55 55 53 83 Temperature(° C.) Number Average 15,500 15,500 15,000 13,500 Molecular Weight (Mn)Molecular Weight 2.7 2.7 2.9 3.2 Distribution (Mw/Mn) Specific Gravity(Kg/m³) 1.13 1.13 1.12 1.11 Mechanical Properties of Polymer TensileStrength (MPa) 85 85 86 85 Tensile Elongation (%) 22 20 20 15 FlexuralModulus (Gpa) 2.9 2.9 2.8 2.9 Notched Izod Impact 58 58 60 50 Strength(J/m) Heat Deflection 75 75 75 98 Temperature (° C.) Water AbsorptionRatio 0.98 0.95 0.88 0.58 (% by weight) Retension ofStrength >95 >95 >95 >95 after UV Irradiation (%) Depth of Crack after0.5 1.0 0.1 no crack CaCl₂ Treatment (μm) Appearance 80 80 80 75 (Glossat 60° C.)

[0119] TABLE 6 Compara- Compara- Compara- Compara- tive tive tive tiveExample Example Example 8 Example 9 10 11 Characteristics of MonomerDicarboxylic Acid ADA/ ADA/ ADA/ ADA/ Component (% by mole) CHDC/ CHDC/TPA/ IPA IPA IPA IPA (82/18) (84/8/8) (84/8/8) (84/8/8) Trans/Cis MolarRatio of 99.7/0.3 45/55 — — CHDA Diamine Component C6DA C6DA C6DA C6DA(% by mole) (100) (100) (100) (100) Characteristics of Polymer MeltingPoint: 260 255 249 240 Tm² (° C.) Melting Enthalpy (J/g) 38 36 44 34Crystallization 220 215 211 192 Temperature (° C.) Glass Transition 6053 50 60 Temperature (° C.) Number Average 15,500 15,500 15,000 15,000Molecular Weight (Mn) Molecular Weight 2.7 2.7 3.1 2.9 Distribution(Mw/Mn) Specific Gravity 1.13 1.13 1.14 1.14 (Kg/m³) MechanicalProperties of Polymer Tensile Strength (MPa) 85 75 83 86 TensileElongation (%) 22 7 25 10 Flexural Modulus (Gpa) 2.9 2.9 2.9 2.9 NotchedIzod Impact 58 45 60 5.1 Strength (J/m) Heat Deflection 78 75 75 75Temperature (° C.) Water Absorption Ratio 1.12 1.00 0.88 1.03 (% byweight) Retension of Strength >95 >95 80 90 after UV Irradiation (%)Depth of Crack after 0.5 2.0 0.1 2.2 CaCl₂ Treatment (μm) Appearance 6580 70 80 (Gloss at 60° C.)

[0120] TABLE 7 Comparative Example 15 Example 16 Example 17 Example 18Example 12 Characteristics of Monomer Dicarboxylic Acid ComponentADA/CHDC ADA/CHDC/IPA ADA/CHDC ADA/CHDC ADA/CHDC (% by mole) (60/40)(84/8/8) (60/40) (60/40) (60/40) Trans/Cis Molar Ratio of CHDA 80/2080/20 80/20 80/20 20/80 Diamine Component (% by mole) C6DA (100) C6DA(100) C6DA (100) C6DA (100) C6DA (100) Characteristics of PolymerMelting Point: Tm² (° C.) 290 257 290 290 288 Melting Enthalpy (J/g) 2536 25 25 24 Crystallization Temperature (° C.) 248 217 248 248 246 GlassTransition Temperature (° C.) 70 55 70 70 68 Number Average MolecularWeight (Mn) 15,500 15,500 15,500 15,500 15,000 Molecular WeightDistribution (Mw/Mn) 2.9 2.7 2.9 2.9 3.0 Specific Gravity (Kg/m³) 1.121.13 1.12 1.12 1.12 Inorganic filler and its compounding GF* GF*GF*/Wollastonite GF*/Mica GF* ratio (parts by wt. based on 100 40 4030/10 30/10 40 parts by wt. of polyamide) Mechanical Properties ofPolymer Tensile Strength (MPa) 210 200 190 190 175 Tensile Elongation(%) 7.5 7.5 5.5 5.5 4 Flexural Modulus (Gpa) 12 12 11 11 12 Notched IzodImpact Strength (J/m) 110 110 90 90 100 Heat Deflection Temperature (°C.) 275 240 275 275 275 Water Absorption Ratio (% by weight) 0.25 0.350.15 0.13 0.25 Retension of Strength after UV >95 >95 >95 >95 >95Irradiation (%) Depth of Crack after CaCl₂ no crack no crack no crack nocrack 0.1 Treatment (μm) Appearance (Gloss at 60° C.) 63 70 60 60 63

INDUSTRIAL APPLICABILITY

[0121] The polyamide of the present invention is a polymer having wellbalanced physical properties and superior characteristics such astoughness, impact properties, heat resistance, light resistance, lightweight, low water absorption, chemical resistance and appearance as wellas an extremely superior moldability, and can be suitably used as amolding material for automotive parts, electric/electronics parts,industrial materials, engineering materials, daily household goods andthe like.

1. A polyamide obtained by thermal polycondensation of (a) dicarboxylicacid components comprising 10 to 80% by mole based on the total moles ofcarboxylic acid components of 1,4-cyclohexanedicarboxylic acid having atrans/cis molar ratio of 50/50 to 97/3 and (b) an aliphatic diaminecomponent.
 2. The polyamide in accordance with claim 1, wherein saidtrans/cis molar ratio of 1,4-cyclohexanedicarboxylic acid is 50/50 to90/10.
 3. The polyamide in accordance with claim 1, wherein saidtrans/cis molar ratio of 1,4-cyclohexanedicarboxylic acid is 55/45 to90/10.
 4. The polyamide in accordance with claim 1, wherein saidtrans/cis molar ratio of 1,4-cyclohexanedicarboxylic acid is 70/30 to90/10.
 5. The polyamide in accordance with claim 3, wherein thedicarboxylic acid component other than 1,4-cyclohexanedicarboxylic acidis an aliphatic dicarboxylic acid having 6 to 12 carbon atoms and/or anaromatic dicarboxylic acid and the aliphatic diamine component is analiphatic diamine unit having 4 to 12 carbon atoms.
 6. The polyamide inaccordance with claim 4, wherein the dicarboxylic acid component otherthan 1,4-cyclohexanedicarboxylic acid is an aliphatic dicarboxylic acidhaving 6 to 12 carbon atoms and/or an aromatic dicarboxylic acid and thealiphatic diamine component is an aliphatic diamine unit having 4 to 12carbon atoms.
 7. The polyamide in accordance with claim 3, wherein thedicarboxylic acid component other than 1,4-cyclohexanedicarboxylic acidis adipic acid and/or isophthalic acid and the aliphatic diaminecomponent is hexamethylenediamine.
 8. The polyamide in accordance withclaim 4, wherein the dicarboxylic acid component other than1,4-cyclohexanedicarboxylic acid is adipic acid and/or isophthalic acidand the aliphatic diamine component is hexamethylenediamine.
 9. Thepolyamide in accordance with claim 7, wherein the dicarboxylic acidcomponents are composed of 10 to 60% by mole of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of 70/30to 90/10, 20 to 90% by mole of adipic acid and 0 to 40% by mole ofisophthalic acid, based on the total moles of1,4-cyclohexanedicarboxylic acid, adipic acid and isophthalic acid asbeing 100%.
 10. The polyamide in accordance with claim 8, wherein thedicarboxylic acid components are composed of 10 to 60% by mole of1,4-cyclohexanedicarboxylic acid having a trans/cis molar ratio of 70/30to 90/10, 20 to 90% by mole of adipic acid and 0 to 40% by mole ofisophthalic acid, based on the total moles of1,4-cyclohexanedicarboxylic acid, adipic acid and isophthalic acid asbeing 100%.
 11. The polyamide in accordance with claim 1, wherein saidpolyamide has a number average molecular weight (Mn) of 7,000 to 100,000and a melting point of 210 to 340° C.
 12. The polyamide in accordancewith claim 4, wherein said polyamide has a number average molecularweight (Mn) of 7,000 to 100,000 and a melting point of 210 to 340° C.13. The polyamide in accordance with claim 7, wherein said polyamide hasa number average molecular weight (Mn) of 7,000 to 100,000 and a meltingpoint of 210 to 340° C.
 14. The polyamide in accordance with claim 8,wherein said polyamide has a number average molecular weight (Mn) of7,000 to 100,000 and a melting point of 210 to 340° C.
 15. The polyamidein accordance with claim 10, wherein said polyamide has a number averagemolecular weight (Mn) of 7,000 to 100,000 and a melting point of 210 to340° C.
 16. A molded article comprising the polyamide in accordance withclaim
 1. 17. A molded article comprising the polyamide in accordancewith claim
 8. 18. A molded article comprising the polyamide inaccordance with claim
 10. 19. A molded article comprising the polyamidein accordance with claim 15.